Method of image reproduction by photo-polymerization and blushing

ABSTRACT

THE LATENT IMAGE ON A PHOTOHARDENABLE MATERIAL WHICH HAS BEEN EXPOSED TO A LIGHT AND SHADOW PATTERN OF ACTINIC LIGHT IS RENDERED VISIBLE BY CONTACTING THE MATERIAL WITH A LIQUID DEVELOPER WHICH IS A NONSOLVENT FOR THE PHOTOHARDENABLE MATERIAL AND WHICH IS SELECTIVELY ABSORBED IN THE UNEXPOSED NONPHOTOHARDENED PORTIONS OF THE MATERIAL   TO CREATE TWO PHASES THEREIN; ONE DISPERSED IN THE OTHER TO PRODUCED A LIGHT SCATTERING VISIBLE LIGHTENED EFFECT IN UNEXPOSED, UNPHOTOHARDENED PORTIONS.

Feb. 9, 1971 J. R. EWING 3,561,962

METHOD OF IMAGE REPRODUCTION BY PHOTOPOLYMERIZATION AND BLUSHING FiledSept. 1. 1966 INVENTOR. JOAN R. EWING ATTORNEY United States PatentOffice 3,561,962 METHOD OF IMAGE REPRGDUCTION BY PHOTO- PGLYMERIZATKONAND BLUSHlN-G Joan R. Ewing, Rochester, N.Y., assignor to XeroxCorporation, Rochester, N.Y., a corporation of New York Filed Sept. 1,1966, Ser. No. 576,649 Int. Cl. G03e 5/00 US. C]. 96-35. 9 ClaimsABSTRACT OF THE DESCLOSURE The latent image on a photohardenablematerial which has been exposed to a light and shadow pattern of actiniclight is rendered visible by contacting the material with a liquiddeveloper which is a nonsolvent for the photohardenable material andwhich is selectively absorbed in the unexposed nonphotohardened portionsof the material to create two phases therein; one dispersed in the otherto produce a light scattering visible lightened effect in unexposed,unphotohardened portions.

This invention relates in general to an imaging process and morespecifically to an imaging system capable of producing blush-likeimages.

Blushing or blooming (the two terms are somewhat synonymous; blushingwill hereafter be used to include both terms) has been defined as asurface coating defect, sometimes associated with lacquers, and isgenerally characterized by the formation of a milky opalescence whichdevelops as the lacquer dries in a humid atmosphere. The Science ofSurface Coatings, edited by H. W. Chatfield, D. Van Nostrand Company,Inc., pp. 465466 (1962).

It has recently been discovered as described in copending applicationSer. No. 522,759, filed Jan. 24, 1966, that blushing rather than beingconsidered as a troublesome defect associated with surface coatings maybe used to advantage to improve the properties of certainelectrophotographic plates useful in the process of xerography. In thebasic xerographic process, for example, as described in Carlson Pat.2,297,691, a xerographic plate comprising a layer of photoconductiveinsulating material on a conductive backing is given a uniform electriccharge over its surface and is then exposed to the subject matter to bereproduced usually by conventional projection techniques. This exposuredischarges the plate areas in accordance with the radiation intensitythat reaches them and thereby creates an electrostatic latent image onor in the photoconductive layer. Development of the latent image iseffected with an electrostatically charged finely divided material suchas an electroscopic powder that is brought into surface contact with thephotoconductive layer and is held thereon electrostatically in a patterncorresponding to the electrostatic latent image. The developed image maybe fixed to the plate or the unfixed image may be transferred to asupport surface, for example, paper to which it may be afiixed by heat,solvent vapors or other means known in the art.

Xerography has found extensive commercial success especially in theoffice copying field and the aforementioned copending applicationimproves the characteristics of certain imaging materials employed inthe xerographic process. However, that application is concerned withxerography and as advantageous a process as xerography is, it doesentail the use of xerographic plates which generally comprise at least atwo-layer system of a photoconductive insulating material overlying aconductive backing layer and generally calls for a charging step whereinthe xerographic plate is brought to a certain surface potential followedby an image exposure step and a developing step and a subsequent fixingstep to perma- 3,561,952 Patented Feb. 9, 1971 nentize the image.Charging usually requires high voltages which introduces the danger ofsparking and requires that the xerographic plate be sensitized orcharged in the dark or in the absence of activating electromagneticradiation. Additionally, the xerographic plate configuration is limitedby the electrical characteristics it must possess in order to accept andretain charge from a charging device. Also fixing is a separate requiredstep if the marking particle image is rendered to be in a form fornormal handling. All these factors and others add additional steps andcomplexity to the xerographic process.

It has also recently been discovered as described in C0- pendingapplication Ser. No. 362,982, filed Apr. 27, 1964, now US. Pat.3,350,205, entitled Blushed Images that blushing may be employed to formimages by drying a surface coating of a photopolymerizable material in ahumid ambient atmosphere to blush the surface of the material which,when followed by exposure and a heat or solvent softening step,selectively erases the blushed surface in image configuration innon-light struck areas. Alternative methods are to expose thephotopolymerizable material, soften it, dry it in a humid ambientatmosphere and soften, or to expose, soften and dry it in a humidambient atmosphere to form blushing in non-light struck areas.

While advantageous, this concept in each of its embodiments calls for athree and four step process which adds to the complexity of the processand in every embodiment calls for drying of a photopolymerizable surfacecoating in a humid ambient atmosphere to produce blushing which issomewhat limiting because of the difiiculty of obtaining and maintaininga suitable supply of water vapor during drying of the photopolymerizablematerial.

It is therefore an object of this invention to provide 7 an imagingprocess which overcomes the above-noted disadvantages.

It is a further object of this invention to provide an imaging processwhich requires no charging step.

It is a further object of this invention to provide an imaging systemwherein the imaging member need not be of xerographic plateconfiguration.

It is a still further object of this invention to provide an imagingprocess capable of producing good continuous tone and solid area imagesas well as line copy images.

It is a still further object of this invention to provide an imagingsystem which is clean and which employs reusable, non-toxic developerliquids.

It is a still further object of this invention to provide an imagingsystem to produce fixed images with no separate fixing step beingrequired.

It is a still further object of this invention to provide an imagingprocess which for certain imaging materials may be carried out in normalroom light.

It is a still further object of this invention to provide an imagingprocess capable of producing blush-like images which process is simplerthan prior art image blushing methods.

It is a still further object of this invention to provide an imagingprocess which employs liquid development to produce a blush-like imageeffect rather than by drying a surface coating in water vapor.

The foregoing objects and others are accomplished in accordance withthis invention by providing an imaging member comprising a layer ofphotohardenable material which is exposed to actinic radiation forexample in imagewise pattern to selectively photoharden said material tocreate a latent image of photohardened and non-photohardened portions.

The latent image is rendered visible by contacting the material with anon-solvent, developer liquid which when selectively absorbed in theunexposed, non-photohardened,

more soluble portions of the material, creates two phases in thematerial, one dispersed in the other to produce a light scattering,visible, lightened efiect in unexposed, nonphotohardened portions.

Some non-solvent developer liquids may be absorbed into thephotohardenable material in sufiicient quantities by their own action toproduce images by this invention.

Alternatively, the non-photohardened portions of the member may berendered more receptive to the non-solvent developer liquid bycontacting the imaging member with a relatively active solvent for thephotohardenable material either prior to or simultaneous with theapplication of the non-solvent developer liquid.

For a better understanding of the invention as well as other objects andfurther features thereof, reference is made to the following detaileddisclosure of the invention taken in conjunction with the accompanyingfigure wherein:

A schematic representation of an exemplary selective blush imagingsystem according to one aspect of the invention is illustrated.

Referring now to the figure, there is seen continuous web imaging memberpassing from supply roll 12 and progressively through exposure station14 and development station 16 to take up roll 20.

Imaging member 10 may comprise almost any photohardenable material 11conventionally used in photomechanical applications in the printing,photoengraving and related arts. A wide variety of photohardenablematerials are found to be incompatible with various non-solvent,developer liquids which when absorbed into the photohardenable material,create two phases in the member one dispersed in the other to produce alight scattering, visible, lightened effect in two phase portions of themember.

It is understood that the photohardenable material 11 will in mostapplications be coated on a suitable rigid or flexible support 13 suchas metal, glass, paper, plastic film or other substrate to lendmechanical support to the photohardenable layer. An alternative approachis to mix the photohardenable material with a binder type material, thislayer optionally supported by a support layer. It the support istransparent the resultant image will not only be directly viewable butmay be used as a transparency in conventional projectors.

The cinnamate esters of polyvinyl alcohol and/or cellulose which may befurther sensitized by the presence of anthrones and their derivatives,polynuclear quinone derivatives and certain ketones such as MichlersKetone and which are commercially available under the trademarks KodakPhotoresist (KPR), KMER and KOR from the Eastman Kodak Co. are found tobe preferred photohardenable materials for use herein because of theexcellent light reflecting images obtained from the process of thisinvention.

However, any suitable photohardenable material may be used. Typicalphotohardenable materials are systems comprising a non-photosensitivepolymer and a photosensitive low molecular-weight compound with which itis capable of reacting on exposure to produce insolubility typified bypolymeric materials such as casein and rubber, in combination withphotosensitive azidostilbene sulfonate derivatives; systems comprising amonomer, a dimer and/or a low-molecular weight polymer with a filler andone or more polymerization catalysts typified by materials as describedin Plambeck Pats. 2,760,863 and 2,791,504; systems comprising anon-photosensitive polymer and photosensitive low-molecular weightcompounds wherein the photosensitive agent reacts with itself onexposure to create insolubility in exposed portions typified byethylcellulose, polymethyl methacrylate and numerous other commercialplastics containing photosensitive chalcone or unsaturated ketonederivatives typified by materials as described in Murray Pat. 1,965,710and Van Deusen Pat. 2,544,905; systems of chromate compounds in colloidssuch as gelatin, albumen and glue or protein colloids sensitized forexample with potassium bichromate or cellulose derivatives sensitizedfor example with ammonium dichromate or other polyvinyls such aspolyvinylalcohol, polyvinylacetal, polyvinyl methyl ether andpolyvinylpyrrolidone sensitized for example with ammonium dichromate orpolyamides sensitized by dichromates; diazo-sensitized materials, andothers.

As the imaging member is unwound from supply roll 12 it passes exposurestation generally designated 14 whereat an original 22 to be reproducedis projected onto the image surface by means of lens 24 operating inconjunction with the lighting means, for example, light bulbs 26, thelens, original and lighting means synchronized by apparatus well knownin the art (not shown) to the motion of member 10. Exposure causes thephotohardenable material to become photohardened in latent image patternconfiguration corresponding to the projected image of original 22. Forexample, if original 22 is a piece of hard copy such as a typewrittenletter, than the latent photohardened pattern on the imaging memberafter exposure will be a negative image of the image on the original thetypewritten or dark image portions being non-exposed on the member tobedevoloped by the process of this invention to form a light scatteringvisible dispersed phase in such non-exposed areas, and the background orwhite portions of the original corresponding to exposed andphotohardened portions of the imaging member which appear afterdevelopment by the process hereof as non-light scattering, relativelydark portions of member 10.

It will be understood by those versed in the art that original 22 may bea transparency such as a conventional photographic negative whereuponexposure of the imaging member may take place by positioning a lightsource above the negative and directing light through it in transparentareas to impinge on the imaging member and photoharden it in imageconfiguration to produce a positive right reading image.

It will be understood that many photohardenable materials are mostsensitive to ultraviolet light which permits the process of thisinvention to be completely carried out in room light without undulyeffecting the sensitivity of the imaging member.

Exposure times may vary over rather Wide ranges and generally are in theorder of times as would be used if the photohardenable material were tobe used in a conventional photomechanical process. Underexposed imagesusually appear as somewhat lighter and more light scattering withslightly lower resolutions than optimumly exposed images. Over-exposedimages usually appear as somewhat darker and less light scattering withslightly lower resolutions than optimumly exposed images.

After exposure the image member is then developed at development station16 whereat brush 28 contacts the member with a quantity of a liquid 32comprising a nonsolvent developer liquid supplied from liquid reservoir30 by connecting tube 34. It will be appreciated that this method ofapplying the liquid to the image member is exemplary and that many othersuitable means exist.

As will be seen the non-solvent developer liquid may be recycled andused many times. For example, a chamber surrounding the imaging memberin the region of brush 28 with ingress and egress ports for member 10would permit evaporation and collection of the liquid 32 used to developthe member. It is found that very little, if any, liquid used indevelopment may not be reclaimed for further use in this or some similarmanner.

For the single treatment development illustrated by the figure, liquid32 may comprise a non-solvent, developer liquid which may be absorbedinto the non-photohardened portions of material 11 in sufficientquantity to produce a two phase, light scattering effect in saidportions. This absorption will generally result because of the inherentpermeability of the photohardenable material itself, even for anon-solvent, to cause the liquid to be absorbed to cause the filmwhitening effect hereof. This mode of development is illustrated inExample XIV.

Alternatively, for single treatment development, liquid 32 may be aliquid mixture comprising a non-solvent developer liquid and an activesolvent for material 11, the solvent to serve as a vehicle to carry thedeveloper liquid into material 11 in non-photohardened portions. In thisaspect of the invention the active solvent component of the liquidmixture should preferably be more volatile than the developer liquid, sothat after absorption of the mixture into the material the solvent isevaporated off first to leave the developer liquid behind in thematerial to create the two phase, visible, light scattering effect inportions where the developer liquid is absorbed.

Preferred volatile, active solvents for use herein may comprise anyfairly volatile, active solvent for the particular photohardenable filmbeing used which is preferably also miscible with or a solvent for theless volatile, developer liquid. A preferred solvent for use herein hasbeen found to be methylene chloride which is a volatile, active solventfor the preferred photohardenable materials described herein and also iscompatible with the less volatile, developer liquids used herein.

Any suitable volatile, active solvent for the particular photohardenablematerial may be used. Typical such solvents for the preferredphotohardenable films described herein include acetone, methanol andmixtures thereof.

The less volatile, non-solvent developer liquid may comprise any liquidcompatible with the volatile, active solvent for the imaging member andwhich being incompatible with the photohardenable material creates twophases in the material, one dispersed in the other, to produce a lightscattering, visible, lightened effect in areas where the developerliquid is absorbed.

Preferred developer liquids for this aspect of the invention are Freon113, a trichlorotrifiuorethane liquid available from E. I. du Pont deNemours & Co., hexamethyl disiloxane, a silicone oil and mixturesthereof. Any suitable liquid which causes a two phase light scatteringeffect in absorbed portions and is a non-solvent for material 11 andpreferably less volatile than the volatile, active solvent component ofthe liquid mixture 32 may be used herein. Typical such liquids mayinclude water, methanol and other aliphatic hydrocarbons and mixturesthereof. The particular liquid chosen will of course depend on the typeof photohardenable material being used and on the properties of thevolatile, active solvent component of the liquid mixture.

It is found that the ratio of components in the liquid mixture forliquid mixtures of preferred solvents and developer liquids to developpreferred photohardenable materials may be varied over a wide range.Parts by volume of the volatile, active, component/less volatile,develover liquid may vary from 4/1 to 1/4 and still produce viewableimages in accordance with the invention.

As an alternative to simultaneously contacting a liquid mixturecomprising an active solvent and a developer liquid to the imagingmember a sequential process may be employed to permit use of developerliquids which evaporate at nearly the same rate or even faster than theactive solvents for a particular photohardenable material. In thisalternative, the latent image is developed by first treating the memberwith an active solvent and then with a suitable developer liquid. Theactive solvent softens the material and makes it receptive to thedeveloper liquid which is then contacted with the member and absorbed innon-photohardened portions to create a two phase, light scatteringeffect in said portions. This alternative is illustrated in Examples XIIand XIII.

It may be desirable for particular liquids and photohardenable materialsto follow the developing with a rinsing step to wash any liquids fromthe developed memher but such a step is not necessary to produce printswith the preferred materials listed herein.

Also, depending on the volatility of the liquids used in development andon development times, it might be found desirable to follow thedeveloping step or the optional rinsing step with a drying steputilizing, for example, heated air blowers. Such a step is not requiredfor preferred liquid mixtures used herein since even the less volatile,developer liquids are sufiiciently volatile to evaporate readily by mereair drying at room temperatures.

It should be noted that while blush-like is used herein, because of thelack of a more descriptive term to describe the resultant effect andimage appearance produced by the liquid development process herein, thecreation of two phases in the imaging member in areas of absorption ofthe non-solvent, developer liquid, one phase dispersed in the other toproduce a light scattering, visible, lightened effect in said portions,although somewhat similar in appearance to the blushing produced whencertain lacquers are dried in a humid atmosphere is thought to be causedby different factors, at least in some instances.

The causes of blushing in lacquers and the blush-like effect inphotohardenable materials by this invention are not completelyunderstood but it is thoughtful that the reason why a two phase systemis created by the process as disclosed herein may be that the long chainpolymers comprising many photohardenable materials are caused to assumea coil form in non-photohardened portions by reaction with non-solventdeveloper liquid, thus causing the light scattering effect dispersedwithin the remainder of the material producing a visible, white or lighteffect in said portions. It is also thought that the blush-like effectproduced by this invention in non-photohardened portions may be causedbecause the developer liquid being incompatible with the materialbecause of its non-solvency may cause the liquid upon being absorbedinto the material to separate in the form of many bubbles to create abubbled or pocketed effect after all liquids are evaporated.

The following examples further specifically define the invention withrespect to the imaging process hereof. Parts and percentages are byWeight unless otherwise indicated. The examples below are intended toillustrate various preferred embodiments of the selective blush-likeimage process of this invention.

EXAMPLE I The liquid photohardenable material KPR from Eastman Kodak Co.is coated on about a 5 mil aluminum substrate and allowed to dry to formabout a A mil layer of KP-R.

The imaging member thus formed is exposed to a photographic negative byfocusing on the member an image produced by a watt Hanovia Utility ModelQuartz Lamp positioned about 7 inches above the member transmittinglight through the translucent portions of the negative for about 5minutes.

The imaging member is then dipped into a liquid mixture of about threeparts by volume of methylene chloride as the more volatile activesolvent and about two parts by volume of about 0.65 centistokehexamethyl disiloxane as the less volatile non-solvent, developerliquid, for about three seconds. i

A faithful right reading, positive, high resolution reproduction of theoriginal appears on the image member with faithful image reproduction ofcontinuous tone and solid area portions of the original.

EXAMPLE II Example I is followed except that the imaging member isdipped after exposure into a liquid mixture of about one part by volumeof methylene chloride as the more volatile active solvent and about twoparts by volume of Freon 113 as the less volatile, non-solvent,developer liquid, for about three seconds.

An image reproduction comparable in quality to the image of Example I isproduced.

7 EXAMPLE 111 An imaging member is made and exposed as in Example Iexcept that exposure is for a period of about 2 minutes.

The member is developed and dried as in Example I to produce a somewhatlighter and more light scattering image with somewhat lower resolutionthan the image produced in Example 1.

EXAMPLE IV An imaging member is made and exposed as in Example I exceptthat exposure is for .a period of about 30 minutes.

The member is developed and dried as in Example I to produce a somewhatdarker and less light scattering image with somewhat lower resolutionthan the image produced in Example I.

EXAMPLE V Example I is followed except that the KPR is coated on blackpaper.

An image is produced with more contrast than the image of Example Ibecause of the darker background areas.

EXAMPLE VI Example I is followed except that the member is dipped intothe liquid mixture for about 20 seconds.

An image is produced with somewhat less contrast than the image producedin Example I resulting from some light scattering even from exposedphotohardened portions of the imaging member.

EXAMPLE VII Example I is followed except that the liquid mixturecomprises about 4 parts by volume of methylene chloride, about 1 part byvolume of about 0.65 centistoke hexamethyl disiloxane and about 1 partby volume of Freon 113.

An image reproduction comparable in quality to the image of Example I isproduced.

EXAMPLE VIII Example I is followed except that the liquidphotohardenable material KOR available from Eastman Kodak Co. is coatedto form the imaging member.

An image results with slightly less contrast, density and resolutionthat the image of Example I.

EXAMPLE IX Example I is followed except that the liquid photohardenablematerial KMER available from Eastman Kodak Co. is coated to form theimaging member.

An image results with slightly less contrast, density .and resolutionthan the image of Example VIII.

EXAMPLE X A solution of about 5 parts RS, 600l,000 second nitrocellulosein about 100 parts ethyl alcohol is saturated with ammonium dichromateand coated on an aluminum EXAMPLE XI Example X is followed except thatthe imaging member after exposure is dipped into a liquid mixture ofabout 4 parts by volume of acetone and about 1 part by volume of waterfor about seconds. An image is produced.

8 EXAMPLE XII About 50 parts of a solution of about 200 parts by volumewater and about 10 parts by volume of polyvinyl methyl ether/maleicanhydride copolymer available from General Aniline and Film Corp. underthe trademark Gantrez 139 is doped with about 1 part ammoniumdichromate, coated on an aluminum substrate and allowed to dry to formabout a 0.2 mil layer of photohardenable material.

The member is exposed as in Example I.

The imaging member is then dipped in methanol for about 1 second andthen dipped in Freon 113 for about 15 seconds.

An image is produced.

EXAMPLE XIII About 50 parts of a solution of about parts of water andabout 10 parts of polyvinyl pyrrolidone is doped with about 1 partammonium dichromate, coated on an aluminum substrate and allowed to dryto form about a 0.5 mil layer of photohardenable material.

The member is exposed as in Example I.

The imaging member is then dipped in a liquid mixture of about equalparts by volume of methanol and acetone for about 1 second and thendipped in acetone for about 15 seconds.

An image is produced.

EXAMPLE XIV About 4 parts of Polectron 450, an emulsion copolymer ofvinyl pyrrolidone-styrene available from General Aniline and Film Corp.is doped with about 1 part ammonium dichromate, coated on Cronarpolyester film available from the E. I. du Pont de Nemours & Co. andallowed to dry to form about a 0.2 mil layer of photohardenablematerial.

The member is exposed as in Example I except that exposure is for aperiod of about 1 hour.

The imaging member is then dipped into water for about three seconds.

An image is produced which appears to fade upon drying but which may beregenerated by rewetting.

Although specific components and proportions have been stated in theabove description of preferred embodiments of the blush imaging systemherein, other suitable materials as listed herein may be used withsimilar results. In addition other materials may 'be added to themixture and variations may be made in the various processing steps tosynergize, enhance or otherwise modify the resultant image. For example,dark pigments or dyes may be added to the photohardenable material toenhance resultant image contrast by decreasing the amount of lightscattering from photohardened light struck portions of the imagingmember. Also photohardenable material support 13 may be darkened or maycomprise a black material to add contrast to the resultant image.

In addition, although the blush-like images produced herein arecustomarily milky or white in color when colorless developer liquids areused, colored developer liqui'ds may be utilized to give colored images.

It will be understood that various other changes in the details,materials, steps and arrangements of parts which have been hereindescribed and illustrated in order to explain the nature of theinvention will occur to and may be made by those skilled in the art upona reading of this disclosure and such changes are intended to beincluded within the principle and scope of this invention.

What is claimed is:

1. An imaging process comprising the steps of:

(a) providing an imaging member comprising a layer of photohardenablematerial;

(b) exposing said material to a light and shadow pattern of actiniclight to selectively photoharden light struck portions of said materialrelative to the nonlight struck portions of said material; and

(c) developing said exposed member, said developing step consistingessentially of contacting said layer of exposed photohardenable materialwith a developer liquid which is a nonsolvent for said photohardenablematerial and which upon being absorbed into the nonli ht struck portionsof said layer creates in said portions at least two phases, onedispersed in the other thereby creating a light scattering visibleeffect in said portions.

2. An imaging process comprising the steps of:

(a) providing an imaging member comprising a layer of photohardenablematerial;

(b) exposing said material to a light and shadow pattern of actiniclight to selectively photoharden light struck portions of said materialrelative to the nonlight struck portions of said material; and

(c) developing said exposed member by simultaneously contacting saidexposed layer of photohardenable material with:

(i) a developer liquid which is a nonsolvent for said photohardenablematerial and which upon being absorbed into the nonlight struck portionsof said layer creates in said portions at least two phases, onedispersed in the other thereby creating a light scattering visibleetfect in said portions; and

(ii) an active solvent for said nonlight struck portions of saidmaterial.

3. An imaging process according to claim 2 wherein said active solventand said developer liquid comprise a liquid mixture.

4. An imaging process according to claim 3 wherein said active solventis more volatile than said developer liquid.

5. An imaging process according to claim 4 wherein said photohardenablematerial comprises a polyvinyl cinnamate.

6. An imaging process according to claim 5 wherein said photohardenablematerial includes a light sensitizer for said polyvinyl cinnamatewhereby the photographic speed of said photohardenable material issubstantially increased.

7. An imaging process according to claim 4 wherein said more volatile,active solvent is selected from the group consisting of methylenechloride, acetone, methanol and mixtures thereof.

8. An imaging process according to claim 7 wherein said developer liquidis selected from the group consisting of hexamethyl disiloxane,trichlortrifluorethane, Water and mixtures thereof.

9. An imaging process according to claim 1 wherein said developer liquidcomprises water.

References Cited UNITED STATES PATENTS 3,350,205 10/1967 Gofie 96-351FOREIGN PATENTS 987,903 3/21965 Great Britain 96-35.1

NORMAN G. TORCHIN, Primary Examiner J. R. HIGHTOWER, Assistant ExaminerU.S. Cl. X.R.

